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Khuk Emergency…Please HELP!!

Discussion in 'Himalayan Imports' started by Eric C, Dec 4, 2007.

  1. Eric C

    Eric C

    162
    Sep 5, 2002
    I redid the handle on my 15AK because I was not satisfied the previous rehandling job I did on it previously. While I was at it, I thought I would reshape the belly a little to make it more even and redo the heat treat on the blade to get a longer hardened zone as well. I followed the instructions I read on other fora (heat to nonmagnetic and quench [warmed vegetable oil]) but the results were just about devastating. This blade hasn’t had a lot of hard use, but it is my favourite from the HI family bar none, so you can imagine how upset I was when I found a crack in the blade after quenching.

    This is what the blade looks like with the new bolster and unfinished handle.
    [​IMG]

    This is a close up of the crack.
    [​IMG]

    Is there anyway of fixing this crack and saving this blade from retirement?

    Thanks in advance
    Eric
     
  2. Keith_H

    Keith_H

    Jul 20, 2007
    sadly, there is not much you can do. re heat-treating is risky- I am surprised how some kukris are edge quenched in water. If you made it beautiful enough, performance may not be an issue :). i would like to know how it cracked, any variables and stresses. sorry about your kukri.
     
  3. Eric C

    Eric C

    162
    Sep 5, 2002
    Thanks Keith.

    I was wondering if it would be possible to weld the crack, re heat-treat with water (I've done that too, with some success on another kukri), and then filing off the excess weld. It won't look as pretty, but will that prevent the crack from lengthening?

    Cheers
    Eric
     
  4. citxmech

    citxmech

    20
    Nov 23, 2007
    Just my two cents. If you just want a reliable "working blade," chalk this one up as tution in the school of hard knocks. But, since your blade is already AFU, you can't really mess it up any more - so why not try to save it if you have the ambition? [which you seem to have - I like where your going with the handle!] If you are going to weld it, you are probably going to need to pull the handle off first. Then you are going to need to anneal the whole thing first to keep from getting stress cracks around the weld. I recommend TIG welding if you have access to it - Less stress than gas and more precise than MIG. make sure your filler rod is suitable, however. Dissimilar metals are a no-no. Realize that welding will warp the blade somewhat and that then you'll have a chance to re-heat treat. Remember, the blade will never be as good as before. When you think about it, a weld is not much different than a cast section joining the two sections of your forged blade. There's really no way to make it perfect without reforging the whole thing.
    Good luck!
     
  5. Eric C

    Eric C

    162
    Sep 5, 2002
    Citxmech

    Thanks for that. I can get access to a TIG, and will try to fill it. Glad you said I had to find a very similar filler rod ... had no idea. Since these are made of car/truck leafspring it is presumably made of 5160. I know nothing about welding, so is there a filler rod similar to that?

    I just read another post in Shop Talk where the same suggestion to fix the crack by TIG welding was discouraged. But like you said it is already AFU :mad:, so if trial goes further south, it becomes a training blade.

    Cheers
    Eric
     
  6. citxmech

    citxmech

    20
    Nov 23, 2007
    Hmm... Were they recommending gas welding or just scrapping it? I like TIG because it offers the most control and the least amount of over-temping of surrounding metal. The inert gas in both MIG & TIG really help with keeping corrosion in the weld. You might want to have a skilled friend do the actual welding. Welding well is very much an art, especially when welding something that goes from thick to very thin. If you do try it yourself, practice on scrap first until you like your results. Also, complete annealing after the welding should help reduce stress around the weld area. Not to sound too anal - but if you are going to use this thing a dye-pen check should identify additional cracks [actually, you might want to do this first - there might be more cracks than just the big one!]
     
  7. citxmech

    citxmech

    20
    Nov 23, 2007
    Eric,
    Here's part of an article on welding 5160:

    Low-Alloy Chromium Steels
    Included in this group are the AISI type 5015 to 5160 and the electric furnace steels 50100, 51100, and 52100. In these steels carbon ranges from 0.12-1.10%, manganese from 0.30-1.00%, chromium from 0.20-1.60%, and silicon from 0.20-0.30%. When carbon is at low end of the range, these steels can be welded without special precautions. As the carbon increases and as the chromium increases, high hardenability results and a preheat of as high 400oC will be required, particularly for heavy sections.
    When using the submerged arc welding process, it is also necessary to match the composition of the electrode with the composition of the base metal. A flux that neither detracts nor adds elements to the weld metal should be used. In general, preheat can be reduced for submerged arc welding because of the higher heat input and slower cooling rates involved. To make sure that the submerged arc deposit is low hydrogen, the flux must be dry and the electrode and base metal must be clean.

    When using the gas metal arc welding process, the electrode should be selected to match the base metal and the shielding gas should be selected to avoid excessive oxidation of the weld metal. Preheating with the gas metal arc welding (GMAW) process should be in the same order as with shielded metal arc welding (SMAW) since the heat input is similar.

    When using the flux-cored arc welding process, the deposited weld metal produced by the flux-cored electrode should match the base metal being welded. Preheat requirements would be similar to gas metal arc welding.

    When low-alloy high-strength steels are welded to lower-strength grades the electrode should be selected to match the strength of the lower-strength steel. The welding procedure, that is, preheat input, etc., should be suitable for the higher-strength steel.

    Source: http://www.key-to-steel.com/default.aspx?ID=CheckArticle&NM=68

    I couldn't find a referance handy for what type of rod to use - but upon further reflection, I would use this blade for "display only" or testing a new profile. If you have access to a dye-pen kit and decide to test it - could you post the results? That test would be very informative for all!
    Thanks!
     
  8. Yangdu

    Yangdu [email protected] Himalayan Imports-Owner Moderator

    Apr 5, 2005
    If you can't save this blade eamil me with your mailing address and I will ship you another 15" AK as free of charge. I want our HI customers and friends to be happy with their Khukuri.
     
  9. Eric C

    Eric C

    162
    Sep 5, 2002
    A. Yangdu,
    Your commitment to customer service is absolutely staggering. I thank you for your amazing offer, but I will not let you foot the bill for this one. I don't think the damage was due to blade defect. It was functioning perfectly well before I attempted the heat treat. The damage, therefore, is entirely my fault. It remains my favorite.
    With grattitude
    Eric
     
  10. Triquetra

    Triquetra Gold Member Gold Member

    755
    Mar 7, 2002
    A perfect example of what a great place HI is and what a great lady Yangdu is.
     
  11. Eric C

    Eric C

    162
    Sep 5, 2002
    Citmech,
    Thanks for the information :). I will mull over that a little later today. Right now... off to work.
    Cheers
    Eric
     
  12. Kismet

    Kismet

    Jan 30, 2002
    Figured that Yangdu might offer.

    Very classy of you not to accept, Eric.:thumbup::):thumbup:




    Kis
    enjoy every sandwich
     
  13. MassMatt

    MassMatt

    707
    Apr 2, 2006
    I agree, classy is the word, both for Yangdu for offering and Eric for declining. HI is rightly famed for standing behind their products but really replacing after trying a do it yourself heat treat is BEYOND "above and beyond".
    Eric I am astounded anyone would attempt such a thing, clearly you have more experience and background in metallurgy etc than I--not to mention cajones.

    I know little about such things but I can't imagine any sort of weld would do more than improve the cosmetics after grinding/polishing it down etc. Could a weld possibly have anything like the strength needed for a user blade?

    Just goes to show how much skill the kamis have got, doing the heat treat with a teapot of water, judging it by the color changes in the metal!
     
  14. Return of the J.D.

    Return of the J.D.

    885
    Nov 29, 2005
    Also, don't you usually heat-treat before the edge is ground down to real sharpness? As I understand it, a sharp edge is often just too thin to take that kind of strain, so most smiths heat-treat after most of the shaping is done, but before the real sharpening takes place. True?
     
  15. Ad Astra

    Ad Astra Gold Member Gold Member

    Jul 30, 2004
    Aye, that was real old-fashioned chivalry on both individual's parts.

    I for one nominate Eric C. to official Good Guy status.

    Understand why you want to save that one- liking the curvy (almost barong-like) handle.


    Mike :cool:
     
  16. Eric C

    Eric C

    162
    Sep 5, 2002
    I thank you for your comments, gentlemen. Under the circumstances, it is only right and a matter of principle that I refused A. Yangdu's gracious offer.

    MassMatt & Return of the JD, I know next to nothing about metallurgy other than what I have read in the fora. So I guess I'm just copy-catting procedure ;) When I first tried hardening a semi sharp khukuri, the flanks of the blade became hard, but the edge remained soft. Maybe I burned the metal because it was too thin. So, I filed the edge to butter knife dullness, reheat-treated and the results improved. I didn't approach it as methodically as i should have, so the above are just my observations.

    I spoke with a friend earlier today and asked if it was possible to do what i wanted with a TIG. He suggested to go with O/A torch instead. To heat the blade evenly before welding to avoid the risk of further fractures. Since I can't get access to a O/A, I might try heating the blade and weld with mild steel filler rod and the TIG (mild steel since 5160 is considered mild steel, I think). I will make sure before I proceed, of course.

    Ad Astra, I have rehandled a few of my HI blades with similar handles. I find the hook a very usefull feature for a snap-cut. :)

    If it goes well, I will post results, but it won't be for some time.

    Cheers
    Eric
     
  17. Sparljo

    Sparljo

    395
    Oct 20, 2006
    Im really digging that handle.... do you have any more pictures of your other rehandled Khuks?
     
  18. eatingmuchface

    eatingmuchface

    154
    Oct 8, 2007
    that handle looks awesome.
    its a shame it cracked.

    not to sound off topic or anything but... how did you get a pic like that?
    its so close up... what kind of camera do you have?
     
  19. Eric C

    Eric C

    162
    Sep 5, 2002
    Sparljo, these are pics of my rehandled PK and 12AK. The PK was perfect until I hit a nail. Now the belly is chipped :grumpy:

    The 12AK gets used most often :)

    [​IMG]

    [​IMG]

    The pic of the cracked blade is only a crop of the original picture. I used the macro setting on an ordinary 5MP digital camera, got as close as possible in good lighting. Hope that helps :)

    Cheers
    Eric
     
  20. Sparljo

    Sparljo

    395
    Oct 20, 2006
    Nice work, thanks for the pics.

    Your Khuks look good and used as well...
     

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